There are different variants of automatic machines for the manufacture, filling and closing of bags, such as mesh bags which house fruit and vegetable products, in which the bags are made from consumable materials such as a continuous tubular mesh and continuous bands of plastic material, gathered in respective portable storages coupled to the machines and from which the material is drawn as the bags are made.
These portable storages are commonly formed by reels, in which the consumable material is wound around a winding core, being able to also adopt other forms in the case of storing gathered continuous tubular mesh compacted in the longitudinal direction.
This type of machine generally comprises a series of support elements in the form of rotating shafts, in which the respective winding cores of the different consumable materials necessary for the manufacture of the bags are coupled, or in the form of a tubular body, on which the storage of tubular mesh longitudinally compacted such that the mesh encompasses the mentioned tubular body is assembled. By way of example and for the manufacture of mesh bags machines comprising a rotating shaft for the firm coupling of a reel which stores the continuous tubular mesh and two rotating shafts for the firm coupling of respective reels of bands of heat-weldable material can be used. For another type of bag in which at least one band of plastic material is used for making a handle, such as that described in patent document EP1988027, machines comprising a tubular body on which a storage of gathered tubular mesh compacted in the longitudinal direction is placed outside, and inside of which the product is introduced in the bag in the course of manufacture, and at least one rotating shaft for the coupling of a reel of a band of heat-weldable material from which the handle of the bags will be formed, are used.
These machines comprise the mechanical means necessary to draw the consumable material required for the manufacture of successive bags from the portable storages and to handle these consumable materials for making them. Conventionally, in the first type of machine described the rotating shafts are motor-driven to facilitate the unwinding of the reels, such that the rotation movement of the shafts is transmitted to the winding core of the reels which rotates together with the corresponding rotating shaft.
It is also known to provide the machines with control units by means of which certain actuation parameters of the mechanical means can be adjusted, such that with one and the same machine bags having different sizes can be manufactured, for example. Furthermore, it is frequent that one and the same machine is used for the manufacture of different types of bags, which require the compliance with different specifications in connection to the material or to the finish, being to that end necessary to replace the reels of consumable material coupled to the rotating shafts with other reels according to the new type of bag. The operation for changing the consumable materials is carried out following a strict control protocol, for the purpose of preventing serious errors which can alter the operation of the machine or lead to the manufacture of erroneous batches of bags.
The first case can take place when the consumable material wound in the reel installed in the machine cannot be handled in accordance with the program for actuating the mechanical means. This situation can occur for example when the heat supplied by the welding means which intervene in the step of closing of the bags is not suitable for the material forming the bands of heat-weldable material. By way of example, the second case can take place when bags obtained from bands printed with different motifs or of different width, or from a mesh having a configuration different from what is desired or demanded by the recipient of the bags, are manufactured.
The main objective of the present invention is to disclose a machine capable of identifying the consumable materials of the portable storages which are coupled to the respective support elements of the machines, for the purpose of assuring that said materials are the suitable ones, in each manufacturing batch, for the production of a predetermined type of bag.
The objective of the present invention is also that the means provided for such effect can be easily installed in pre-existing machines, without being necessary to redesign or replace a significant number of components of the machines, and therefore that their installation is not too expensive or complicated.
Patent document EP 1266830 discloses a system for identifying in a machine for the manufacture of packaging material a consumable material which is supplied in the form of a band, the system including means for radiofrequency communication between said material in the form of a band and the machine. Said communication means comprise an antenna suitable for the remote reading of the data stored in a transponder housed in the winding core of the consumable material.
The described system has no direct application for the first type of machine to which reference is made in the present invention, since only information of a single consumable material the winding core of which is in addition coupled to a rotating shaft preferably of a plastic material is obtained.
Apart from the fact that the rotating shafts of the pre-existing machines are conventionally metallic, which causes interferences in the radiofrequency communication, the fact that the machines are provided with a plurality of rotating shafts for the coupling of different windings of consumable material necessary to make one and the same bag, together with the fact that said rotating shafts are arranged not too far from one another, involves an added difficulty if individual information is to be obtained from each of said materials without the proximity of the different cores generating interferences in the radiofrequency communication, all this without giving up a broad enough reading field to detect radiofrequency tags applied on the winding core when the latter adopts different angle positions during its rotation.
Furthermore, in the event that the mentioned rotating shafts are motor-driven, a variant that is not reflected in the system described in document EP 1266830, the proximity of the drive motor, the metallic nature of its components and even the attraction magnetic field of the rotor also affect the reading field of the corresponding antenna, which up until now has discouraged the person skilled in the art to contemplate the solution described in EP1266830 as a solution applicable to the specific sector of the invention. However, if the mentioned drawbacks are removed, the radiofrequency communication is very suitable for solving the problem considered.
A secondary objective of the present invention therefore is to provide the machine with radiofrequency communication means which overcome the aforementioned drawbacks.